1. Field of the Invention
This invention relates generally to cassettes containing an information recording medium, and more specifically to a cassette mechanism for indicating whether the cassette is in a recording or non-recording condition.
2. Description of the Prior Art
U.S. Pat. No. 4,409,630 which issued to Saito on Oct. 11, 1983 discloses a slidable member supported between upper and lower plates for preventing inadvertent erasure of the information signals from an information recording medium. The slidable member has a body portion provided with an extending finger formed by a slot. The finger has a projection at its free end adapted to selectively seat in one of a pair of spaced grooves upon movement of the slidable member between recording or non-recording positions. In the recording position of the slidable member, the interfacing recording device will record information on a previously unrecorded medium. In the non-recording position, the interfacing recording device is prevented from recording so that a previous recording on the medium will not be inadvertently erased.
An apparatus for preventing erasure of previously recorded material by placing the casette in a non-recording mode of operation is disclosed in U.S. Pat. No. 4,460,930 which issued to Takahashi on July 17, 1984. The apparatus comprises a piece formed simultaneously with the disk cassette cover by a molding process. The piece has a configuration which enables it to be slidably remounted to the disk cover after being torn off the cover.
U.S. Pat. No. 4,517,617 which issued to Tsuji et al. on May 14, 1985 discloses a cassette having a channel-shaped cut-out portion at a corner thereof. An erasure preventing piece at the corner is connected integrally with the cassette through a thin portion formed by a V-shaped groove. The piece can be separated from the cassette by pivoting it outwardly and breaking it off so that when the cassette is placed in an interfacing recording device, it will not operate to inadvertently erase a previously recorded medium.